22 research outputs found
Daksha: On Alert for High Energy Transients
We present Daksha, a proposed high energy transients mission for the study of
electromagnetic counterparts of gravitational wave sources, and gamma ray
bursts. Daksha will comprise of two satellites in low earth equatorial orbits,
on opposite sides of earth. Each satellite will carry three types of detectors
to cover the entire sky in an energy range from 1 keV to >1 MeV. Any transients
detected on-board will be announced publicly within minutes of discovery. All
photon data will be downloaded in ground station passes to obtain source
positions, spectra, and light curves. In addition, Daksha will address a wide
range of science cases including monitoring X-ray pulsars, studies of
magnetars, solar flares, searches for fast radio burst counterparts, routine
monitoring of bright persistent high energy sources, terrestrial gamma-ray
flashes, and probing primordial black hole abundances through lensing. In this
paper, we discuss the technical capabilities of Daksha, while the detailed
science case is discussed in a separate paper.Comment: 9 pages, 3 figures, 1 table. Additional information about the mission
is available at https://www.dakshasat.in
Science with the Daksha High Energy Transients Mission
We present the science case for the proposed Daksha high energy transients
mission. Daksha will comprise of two satellites covering the entire sky from
1~keV to ~MeV. The primary objectives of the mission are to discover and
characterize electromagnetic counterparts to gravitational wave source; and to
study Gamma Ray Bursts (GRBs). Daksha is a versatile all-sky monitor that can
address a wide variety of science cases. With its broadband spectral response,
high sensitivity, and continuous all-sky coverage, it will discover fainter and
rarer sources than any other existing or proposed mission. Daksha can make key
strides in GRB research with polarization studies, prompt soft spectroscopy,
and fine time-resolved spectral studies. Daksha will provide continuous
monitoring of X-ray pulsars. It will detect magnetar outbursts and high energy
counterparts to Fast Radio Bursts. Using Earth occultation to measure source
fluxes, the two satellites together will obtain daily flux measurements of
bright hard X-ray sources including active galactic nuclei, X-ray binaries, and
slow transients like Novae. Correlation studies between the two satellites can
be used to probe primordial black holes through lensing. Daksha will have a set
of detectors continuously pointing towards the Sun, providing excellent hard
X-ray monitoring data. Closer to home, the high sensitivity and time resolution
of Daksha can be leveraged for the characterization of Terrestrial Gamma-ray
Flashes.Comment: 19 pages, 7 figures. Submitted to ApJ. More details about the mission
at https://www.dakshasat.in
Antioxidant activity of tannoid principles of <i>Emblica officinalis </i>(amla) in chronic stress induced changes in rat brain
877-880Effect of tannoid principles emblicanin A,
emblicanin B, punigluconin, and pedunculagin of E. officinalis was assessed
on chronic unpredictable footshock-induced stress-induced perturbations in
oxidative free radical scavanging enzymes in rat brain frontal cortex and striatum.
Chronic stress, administered over a period of 21 days, induced significant increase
in rat brain frontal cortical and striatal superoxide dismutase (SOD) activity,
concomitant with significant reduction in catalase (CAT) and glutathione peroxidase
(GPX) activity. The changes in the enzyme activities was accompanied by an
increase in lipid peroxidation, in terms of augmented thiobarbituric acid-reactive
products. Administration of Emblica tannoids (10 and 20 mg, po) for 21 days, concomitant
with the stress procedure, induced a dose-related alteration in the stress
effects. Thus, a tendency towards normalization of the activities of SOD, CAT and
GPX was noted in both the brain areas, together, with reduction in lipid peroxidation.
The results indicate that the reported antistress rasayana activity of E.
officinalis may be, at least partly due to its tendency to normalize stress-induced
perturbations in oxidative free radical scavenging activity, in view of the postulate
that several stress-induced diseases, including the process of aging, may be related
to accumulation of oxidative free radicals in different tissues
Effect of <i>Emblica officinalis </i>tannoids on a rat model of tardive dyskinesia
945-947Effect of active tannoid principles of E.
officinalis, comprising of emblicanin A (37%), emblicanin B (33%),
punigluconin (12%) and pedunculagin (14%), was investigated on a rat model of tardive
dyskinesia (TD) induced by once daily administration of haloperidol (1.5 mg/kg,
ip) for 28 days. Involuntary oro facial movements (chewing movements, buccal
tremors and tongue prolusion) were assessed
as TO parameters. The tannoid principles of £.officina/is (EOT) wery
administered concomitantly with haloperidol in the doses of 10, 20 and 50
mg/kg, po, for 28 days. Sodium valproate (200 mg/kg, po), a Gaba-mimetic agent,
and vitamin E (400 mg/kg, po), an antioxidant, were used as the standard drugs
and administered for the same period. EOT induced a dose-related inhibition of
all the three TD parameters assessed, as did vitamin E. The effect of sodium
valproate remained statistically insignificant. The results suggest that EOT
exerts a prophylactive effect against neuroleptic-induced TD which is likely to
be due to its earlier reported antioxidant effects in rat brain areas, including
striatum
Adaptogenic activity of Siotone, a polyherbal formulation of Ayurvedic rasayanas
119-128Siotone (ST) is a herbal formulation comprising
of Withania somnifera, Ocimum sanctum, Asparagus racemosus, Tribulus
terristris and shilajit, all of which are classified in Ayurveda as rasayanas
which are reputed to promote physical and mental health, improve
defence mechanisms of the body and enhance longevity. These attributes are similar to
the modern concept of adaptogenic agents, which are, known to afford protection
of the human physiological system against diverse stressors.
The present study was undertaken to investigate the adaptogenic activity of ST against
chronic unpredictable, but mild, footshock stress induced perturbations in
behaviour (depression), glucose metabolism, suppressed
male sexual behaviour, immunosuppression
and cognitive dysfunction in CF strain albino rats. Gastric ulceration,
adrenal gland and spleen weights, ascorbic acid and corticosterone concentrations
of adrenal cortex, and plasma corticosterone levels, were used as the
stress indices. Panax ginseng (PG) was used as the standard adaptogenic agent
for comparison.
Additionally, rat brain levels of tribulin
, an endogenous endocoid postulated to be involved in stress, were also assessed in
terms of endogenous monoamine oxidase (MAO) A and MAOB inhibitory activity. Chronic
unpredictable footshock induced marked gastric ulceration, significant
increase in adrenal gland weight and plasma corticosterone
levels, with
concomitant decreases in spleen weight, and concentrations of adrenal gland
ascorbic acid and corticosterone. These effects were
attenuated by ST (50 and 100 mg/kg, p.o) and PG (100 mg/kg, p.o), administered once
daily over a period of 14 days, the period of stress induction. Chronic stress
also induced glucose intolerance, suppressed male sexual behaviour.
Induced behavioural depression (Porsolt 's swim despair test and learned helplessness
test) and cognitive dysfunction (attenuated retention of learning in active and
passive avoidance tests), and immunosuppression (leucocyte migration inhibition
and sheep RBC challenged increase in paw oedema in sensitized rats). All these chronic
stress-induced perturbations were attenuated, dose-dependently
by ST (50 and 100 mg/kg, p.o.) and PG (100 mg/kg, p.o.). Chronic stress-induced increase in rat brain tribulin activity
was also reversed by these doses of ST and by PG. The results indicate that ST has significant
adaptogenic activity, qualitatively comparable to PG, against a variety of behavioural,
biochemical and physiological perturbations induced by unpredictable
stress, which has been proposed to be a better indicator of clinical stress than
acute stress parameters. The likely contribution of the individual constituents
of ST in the observed adaptogenic action of the polyherbal formulation, have been
discussed
<span style="font-size:14.0pt;line-height: 115%;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language: HI" lang="EN-IN">Antioxidant activity of active tannoid principles of <i>Emblica officinalis </i>(amla)</span>
676-680The
antioxidant activity of tannoid active principles of E. officinalis consisting
of emblicanin A (37%), emblicanin B (33%), punigluconin (12%) and pedunculagin
(14%), was investigated on the basis of their effects on rat brain frontal
cortical and striatal concentrations of the oxidative free radical scavenging
enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase
(GPX), and lipid peroxidation, in terms of thiobarbituric acid-reactive
products. The results were' compared with effects induced by deprenyl, a
selective monoamine oxidase (MAO) B inhibitor with well documented antioxidant
activity. The active tannoids of E. officinalis (EOT), administered in the
doses of 5 and 10 mg/kg. i.p .. and deprenyl (2 mg/kg, i.p.), induced an
increase in both frontal cortical and striatal SOD, CAT and GPX activity, with
concomitant decrease in lipid peroxidation in these brain areas when
administered once daily for 7 days. Acute single administration of EOT and
deprenyl had insignificant effects. The results also indicate that the
antioxidant activity of E. officinalis may reside in the tannoids of the fruits
of the plant, which have vitamin C-like properties, rather than vitamin C
itself.
Hyperglycaemia in pregnancy: Effects on the offspring behaviour with special reference to anxiety paradigms
231-236Maternal hyperglycemic effect was studied
on the offspring behaviour. Offspring were obtained from diabetic rats by mating
a normal father with a diabetic mother (NFDM), diabetic father with normal
mother (DFNM) and diabetic father with diabetic mother (DFDM). Rats were
rendered diabetic by injecting streptozotocin (STZ, 50 mg/kg IP) in citrate
buffer. Offspring were subjected to various anxiety parameters including open
field exploratory behaviour, elevated plus maze and zero maze behaviours, and the
social interaction tests at the age of 8 weeks. The results indicate that
offspring of NFDM and
DFDM showed anxiogenic activity on the
elevated plus maze zero maze and the social interaction test. Offspring of NFDM
and DFDM exhibited hyper and emotional activity in the open field behaviour
test. The behavioural alterations observed in the offspring were comparable to
the behavioural alterations noted in STZ diabetic rat as reported earlier.
Further offspring of NFDM and DFDM exhibited mild hyperglycaemia. No
significant behavioural alterations in the offspring of DFNM were observed. It
may be concluded, that exposure of offspring to diabetic environment in their
foetal life can lead to anxiogenic/emotional behaviours in adult life